Does anyone have experience or thoughts (good and bad) on underground rainwater harvesting? Under the driveway and/or under the foundation? I'm talking with a company tomorrow who has a system that can go under the driveway (which seems pretty straight forward) but also a system that goes INTO the foundation, as "free form Aquifers that will take the place of the normal road base used to fill the voids in the foundation.".

I would just be concerned about putting water in/near the foundation. What if it leaks?

Not sure about the costs yet either. We have to incorporate pervious concrete into our driveway plans to be under the impervious sq ft requirements, but I believe that we can also offset impervious with rainwater harvesting. So maybe the cost of doing the underground will be less than the cost to use pervious concrete.